Paleomagnetic study of igneous rocks from the Manicouagan Structure, Quebec

Abstract

The Lower Triassic Manicouagan group is comprised of breccia, basalt diorite, and andesite, forming flat sheets partly filling a structural depression in Precambrian rocks. Cored, oriented samples show remarkably stable thermoremanent magnetization. Statistical analysis of the data shows that formation of the Manicouagan group has taken 10,000 years or less. Comparison with other Triassic pole positions from North America suggests that the area north of the St. Lawrence River has not rotated with respect to the rest of the continent since Triassic time.